Pull the steak out of the fridge to come to room temperature. While the steak is warming up, make the chimichurri. Finely chop the fresh dill and chives. Add them to a bowl along with all of the other ingredients for the chimichurri. Set aside.
Pat the steak with paper towels to remove any extra moisture. Season with salt and pepper on both sides. Add avocado oil to a cast iron skillet over high heat. Once the oil is hot, add the steak to the pan.
Let the steak cook for 2-3 minutes, then flip. You should have deep color and a great sear on the first side. Let the steak cook on the other side for 1 additional minute. Then, turn the heat down, and add the butter and garlic to the pan. Use a spoon to scoop the butter on top of the steak, over and over, for a minute. This is basting the steak and adds a lot of flavor. After one minute, remove the steak from the heat.
Let the steak rest for 5-6 minutes. After the steak has rested, slice it against the grain. Top with plenty of chimichurri and enjoy!